A large number of medicament delivery devices for self-administration have been developed the last decades. Many of these devices utilize injection needles that penetrate the skin of the patient for delivery of a dose.
Some devices have automatic mechanisms for penetration and subsequent injection of medicament. While providing a degree of automation and less manual handling by the patient, some persons feel uneasy using such devices, for instance when they cannot fully control penetration and/or injection.
During the years, a number of the devices have used syringes as medicament containers where an injection needle is an integral part of the container. The distal end of the injection needle is in constant contact with the medicament and the needle is tubular, i.e. there is a small passage through the needle.
For some types of medicament, or for some applications, such an arrangement is unsuitable since air may enter through the passage of the needle and may adversely affect the medicament. Also, the injection needle and/or the medicament can be adversely affected by the contact between the metal of the needle and the chemicals of the medicament.
Other types of common medicament containers are so called medicament cartridges, which have a neck or connection portion at one end of the container, where the neck portion often is arranged with a penetrable wall, a septum. A suitable injection needle is then connected to the neck portion, where the connection members may comprise threads, bayonet fittings, luer locks, just to mention a few. The advantage is that the interior of the medicament container, or cartridge, and its contents are sealed off from the environment until an injection needle is attached and the septum is pierced.
A drawback of this solution is that a user or patient has to perform assembly steps in order to attach the injection needle to the cartridge, which may be difficult for some persons who suffer from reduced manual dexterity, etc. Also, if there is an emergency situation where a patient or user needs his/her medication quickly, assembly steps may be very disturbing and stressful. Further, attachment of an injection needle to a cartridge most often requires a subsequent placement of the assembled needle/cartridge in a medicament delivery device since it is much easier to perform the assembly outside the medicament delivery device. Thus, further handling steps are required before the device is ready to deliver a dose.
In order to handle these drawbacks, some devices have been developed such that during activation, the connection of an injection needle to a cartridge type medicament container is achieved.
For example, document WO 2012/022810 discloses a device where an injection needle having a proximal pointed end and a distal pointed end is arranged inside a device, and wherein a medicament cartridge is brought in contact with the distal pointed end when the device is to be used. Before use, both ends of the injection needle are kept sterile by protective sheaths. These sheaths are pierced and compressed during use of the device.
A drawback of this device is that the handling sequence is not optimal. '810 describes that a penetration step with the proximal end of the injection needle is performed before the distal end penetrates the septum of the cartridge. During the penetration step, a contactor is pushed in the distal direction, exposing the injection needle. The end of the penetration should then first trigger a penetration of the septum and should then trigger a subsequent release of the plunger rod for expelling a dose of medicament. Thus, there is no priming of the medicament container before injection, and there are several steps that need to be performed after penetration in order to provide an injection. Further, the safety aspects are minimal in that only a cover has to be removed before the device is ready and active. There is no further mechanism for locking the contactor until use and there is therefore a risk that someone may be pricked by accidentally pushing the contactor in the distal direction.
Another document describing the handling of the above mentioned drawbacks is WO 2012/025639. It discloses a number of embodiments of a device comprising an injection needle with both distal and proximal pointed ends, wherein a medicament container is pierced only when the device is to be used. The document does not deal with any enhanced safety aspects and some of the embodiments do not have any means for shielding or protecting the injection needle before or after use.
Regarding safety aspects, document U.S. Pat. No. 7,794,432 discloses a medicament delivery device provided with a safety mechanism in the form of a safety pin arranged at a distal end of the device. The safety pin is designed to engage a collet of a power pack such that it prevents the end of the collet from compressing, in turn preventing actuation of the device. When the device is to be used, the safety pin is removed whereby the device is ready for actuation.
The safety pin of '432 is a simple blocking member that does not perform any other actions than preventing compression of the collet. When removed, the collet could be compressed by rough handling of the device, leading to unintentional premature dose delivery. Further, the device of '432 is arranged with a conventional medicament container, leading to the above mentioned problems.